Chapter 141:6-7Laws of the Megillah

6. On Purim, the prayer "Al Ha'Nissim", is recited in the Sh'mone Esrei
of "Ma'ariv," "Shacharis" and "Mincha." If one forgot to recite it, the
same laws as Chanukah apply (See HY 139:21).

7. Every person, man and woman, is obligated to hear the reading of the
Megillah at night and during the day [of Purim]. Therefore, even the young
single girls should go to synagogue [to hear the reading]. If they do not
go, someone must read for them at home. Even young children must be
educated to go to hear the Megillah, however, very young children should
not be brought to synagogue because they disturb the concentration of those
listening.